For diverse purposes, it is desirable to transfer a liquid from a container to an other in a closed system, especially for filling and/or emptying an anesthetic vaporizer with an anesthetic in the liquid form. Indeed, it is important for the protection of the staff, to avoid the diffusion of the anesthetic in the working area.
For example, U.S. Pat. No. 5,144,991 describes an arrangement for filling and emptying an anesthetic vaporizer with an anesthetic liquid from a supply vessel by means of a filling channel. The filling arrangement includes a venting channel and a connecting piece adapted to fit on an anesthetic vaporizer and has a blocking device which is mounted in the channel assembly of the filling channel and venting channel.
U.S. Pat. No. 3,536,107 discloses a container provided with air vent means having gravity actuated means controlling the air vent means when the container is upright or inverted. The use of a ball, moving in a housing and with respect to a ball seat, by reason of gravity, to obturate or liberate openings, is disclosed in U.S. Pat. No. 4,531,659 and U.S. Pat. No. 2,991,897.
It is well known in the art that when an open neck container containing a liquid is turned upside-down, the flow of liquid may be impeded by a vacuum created in the container. This phenomena is called "gas-lock", especially "air-lock". An example of such an "air-lock" was noted when a volume of air is trapped by a liquid in the bottom of the first container and prevent it to flow in the venting channel after the container was turned upside-down.
U.S. Pat. No. 4,705,195 discloses a liquid dispenser which includes a pump chamber, connected to a storage chamber, and a valve body extending through the passage and controlling the liquid flow. This device is not adapted to a closed system, considering that it has no separating channels for the liquid and the gas.
Therefore, there is a very strong need for a device and a method allowing to transfer a liquid in a closed system without having the problems noted with devices of the prior art.